sessioncommunities.online/php/servers/tags.php

<?php
	require_once 'utils/utils.php';

	class TagType {
		private function __construct() {}
		const USER_TAG = 0;
		const RESERVED_TAG = 1;
		const WARNING_TAG = 2;
	}

	class CommunityTag implements JsonSerializable {
		public function __construct(
			string $text,
			int $tag_type = TagType::USER_TAG,
			string $description = ""
		) {
			$this->text = $text;
			$this->type = $tag_type;
			$this->description =
				empty($description) ? "Tag: $text" : $description;
		}

		public readonly int $type;

		public readonly string $text;

		public readonly string $description;

		/**
		 * Returns a lowercase representation of the tag for purposes of de-duping.
		 */
		public function __toString(): string {
			return strtolower($this->text);
		}

		/**
		 * Returns a lowercase representation of the tag for use in display.
		 */
		public function get_text(): string {
			return strtolower($this->text);
		}

		public function jsonSerialize(): mixed {
			// Only used for passing to DOM
			$details = get_object_vars($this);
			$details['text'] = html_sanitize($this->get_text());
			$details['description'] = html_sanitize($details['description']);
			$details['type'] = $this->get_tag_type();
			return $details;
		}

		private static function preprocess_tag(?string $tag) {
			$tag = trim($tag);

			if (strlen($tag) == 0) {
				return $tag;
			}

			$tag = html_sanitize(html_entity_decode($tag));

			if ($tag[0] == '#') {
				return substr($tag, 1);
			}

			return $tag;
		}

		/**
		 * @param string[] $tag_array
		 * @return \CommunityTag[]
		 */
		private static function from_tag_array(array $tag_array) {
			$tags = array_map(function(?string $tag) {
				return CommunityTag::preprocess_tag($tag);
			}, $tag_array);

			$tags = array_filter(
				$tags, function(?string $tag) {
					return strlen($tag) != 0;
				}
			);

			return array_map(function(string $tag) {
				return new CommunityTag($tag);
			}, $tags);
		}

		/**
		 * Returns the user tags given, without any reserved tags.
		 * @param string[] $tags
		 * @param bool $remove_redundant Removes duplicate and obvious tags.
		 * @return \CommunityTag[]
		 */
		public static function from_user_tags(
			array $tags, bool $remove_redundant = false
		): array {
			$tags_user = array_filter(
				$tags,
				function($tag) {
					return !CommunityTag::is_reserved_tag($tag);
				}
			);

			$tags_built = CommunityTag::from_tag_array($tags_user);

			if ($remove_redundant) {
				$tags_built = CommunityTag::dedupe_tags($tags_built);
				$tags_built = array_filter($tags_built, function(\CommunityTag $tag) {
					$text = strtolower($tag->text);
					return !in_array($text, CommunityTag::REDUNDANT_TAGS);
				});
			}

			return $tags_built;
		}

		/**
		 * @param string[] $details_array Array of string tags.
		 * @return \CommunityTag[]
		 */
		public static function from_details_array(array $details_array): array {
			return CommunityTag::from_user_tags($details_array);
		}

		/**
		 * @param \CommunityTag[] $tags
		 * @return \CommunityTag[]
		 */
		public static function dedupe_tags(array $tags) {
			return array_unique($tags);
		}

		public function get_tag_classname(): string {
			$tag_type = $this->get_tag_type();
			$classname = "room-label-$tag_type";
			if (CommunityTag::is_showcased_tag($this->text)) {
				$classname .= " room-label-showcased";
			}
			return $classname;
		}

		public function get_tag_type(): string {
			return match($this->type) {
				TagType::USER_TAG => 'user',
				TagType::RESERVED_TAG => 'reserved',
				TagType::WARNING_TAG => 'warning'
			};
		}
		/**
		 * @var string[] RESERVED_TAGS
		 * Array of derived tags unavailable for manual tagging.
		 */
		private const RESERVED_TAGS = [
			"official",
			"nsfw",
			"new",
			"modded",
			"not modded",
			"read-only",
			"uploads off",
			"we're here"
		];

		private const SHOWCASED_TAGS = ["official", "new", "we're here"];

		private const REDUNDANT_TAGS = ["session"];

		public const NSFW_KEYWORDS = ["nsfw", "porn", "erotic", "18+"];

		public const CHECK_MARK = "✅";

		public const WARNING_ICON = "⚠️";

		/**
		 * Checks whether the given manual tag can be accepted.
		 */
		public static function is_reserved_tag(string $tag): bool {
			return in_array(strtolower($tag), CommunityTag::RESERVED_TAGS);
		}

		public static function is_showcased_tag(string $tag): bool {
			return in_array(strtolower($tag), CommunityTag::SHOWCASED_TAGS);
		}
	}
?>